Climate change is nothing unnatural. The earth's climate has always kept changing throughout its existence. The ice ages are very extreme examples of this. But the
climate change which takes place at the moment was caused by mankind and leads to changes that happen approximately 50 times faster than all previous ones.

Causes

Main cause for the climate change is the strong increase of CO2 (carbon dioxide) and other anthropogenous gases (e.g. FCKW) in the earth's atmosphere. A small amount of it can be traced back to natural origins, such as variation of the sun's activity.
Carbon dioxide

The radiation budget of the earth changes, temperatures in the troposphere begin to rise. Deglaciation sets in. Sea levels rise and acidity commences. Because of the rising temperatures condensation increases in certain areas, de­creases in others. Permafrost soils in Siberia, Canada, Greenland and Alasca melt and release more carbon dioxide, accelerating the process.
The sensitive ecologic system of the earth becomes unbalanced, climate zones shift, coast lines change, new deserts come into being, habitats of humanity move, animal and plant species become extinct.